Growth failure and developmental delays are characteristic problems of very premature neonates and nonorganic failure-to-thrive infants. Inadequate stimulation has been implicated as a potential contributor to these delays. Although attempts to stimulate growth and development have yielded inconclusive data, research on maternally deprived rat pups suggested that a specific pattern of tactile stimulation may be necessary for normal mechanisms of growth and cellular developmental biochemistry. In a preliminary study we have documented the positive effects of a similar type of stimulation on the growth and behavior of preterm neonates. The purpose of the present proposal is to investigate the effects of this tactile/kinesthetic intervention on very premature neonates and nonorganic failure-to-thrive infants, hoping to prevent and ameliorate growth and developmental delays in these infants. In accord with the rat pup model and to understand the underlying mechanisms whereby stimulation facilitates growth, as well as behavioral and physiological organization, several variables will be assessed including sleep-wake behavior and physiology, activity level, growth curves, growth hormone, somatomedin C, cortisol and catecholamines. The effects of tactile/kinesthetic stimulation on these functions will be studied in a treatment/control group paradigm and a repeated measures stimulation/no stimulation design. A comparison will also be made between a tactile and a kinesthetic stimulation group, since preliminary data suggest that these two forms of stimulation may have different effects. Finally, follow-up assessments will be made to determine any prolonged effects of this stimulation program on growth and development. Based on our pilot data we hypothesize that our tactile/kinesthetic intervention program will prevent growth failure and developmental delays in both premature and nonorganic failure-to-thrive infants. The stimulation will hopefully facilitate more organized sleep-wake behavior, feeding behavior and weight gain. These developments may lead to shorter hospitalization and shorter periods of separation from parents with an associated significant reduction in hospital costs. The greater growth and behavioral organization of the infants should failitate early mother-infant interactions and improved performance on developmental assessments which in turn can contribute to superior later development. If this stimulation program is effective, it is sufficiently simple to ultimately be incorporated into routine neonatal care, infant nursery and parent training programs.